function

function declaration.

📝Syntax

function [out_1,...,out_M,varargout] = fname(in_1, ... , in_N, varargin)
function fname(in_1, ... , in_N, varargin)
function [out_1,...,out_M,varargout] = fname()
function fname()
function nestedFunction(...), statements, end
function fname(...), statements, end
script statements, function localFunction(...), statements, end, script statements

📄Description

function opens a function definition.

end closes a function definition. The legacy endfunction keyword is not supported.

Function files may end at end-of-file for simple function bodies, but explicit end is required to close nested functions, local functions, and block constructs unambiguously.

A function may be written on a single line by placing a , or ; after the signature, for example function y = f(x), y = x + 1; end.

Function files can contain local functions after the main function. Script files can contain local functions interleaved with executable script statements: a local function may appear before, between, or after script statements, and script statements may follow a local function definition.

Local functions in scripts must be closed with an explicit end. Nelson still rejects local functions declared inside open statement contexts such as if, for, while, switch, and try.

Nested functions are supported inside parent function bodies. Nested functions can read and update variables from their parent function workspace, and handles to nested functions keep their captured state.

💡Examples

in a file: demo_function.m

function r = demo_function(a, b)
  r = a + b;
end

Nested function sharing a parent variable.

function y = nested_demo(x)
  scale = 2;
  y = inner(x);

  function r = inner(v)
    r = v * scale;
  end
end

Script with trailing local functions.

x = local_add_one(41);

function y = local_add_one(v)
  y = v + 1;
end

Script with local functions interleaved between statements.

a = 10;

function y = times_two(v)
  y = v * 2;
end

b = times_two(a);

function z = minus_one(v)
  z = v - 1;
end

c = minus_one(b)

🕔Version History

Version	Description
1.0.0	initial version
2.0.0	local functions can be interleaved with script statements.

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